Expansion wedge



' ver .in Tristar nl vn t. lilla il latent F CHAMBERSBURG, PENNSYLVANIA.

XPANSON l/VEDGE.

Application filed October 11, 1921.

To all whom t may concern.'

Be it known that l, lWILLmM H. DERBY- srnnn, Jr., a citizen of theUnited States, residing in Chambersburg, Pennsylvania, have invented anExpansion l/Vedge, of which the following is a specification.

The object of this invention is to provide means lfor compensatinguneven expansion or contraction in two associated elements of astructure, the invention iinding a particularly valuable application todrop hammers and similar machines comprising an anvil and an anvil capdetachably secured therein.

ln machines ot the type mentioned, it is customary to maire the anvil ofcast steel andthe cap ot Yforged steel, and when during operation ot themachine the parts become heated there is an unequal expansion tending toloosen the` cap in the anvil, the latter having; the higher coeiiicientol5 expansion and expandingl more rapidly under the etlects ol the heat.lt is the practice to employ a wedge to secure the cap to the anvil, andthis wedge during` operation or" the machine is periodically7 driven into retain the cap securely to its seat and to prevent its displacementon the anvil.

Also when operation or the machine is discontinued and the partsgradually cool, the cast metal anvil contracts more rapidly than theforged cap, and unless the wedge iS driven out or loosened to permitlree contraction, there invariably results damage to one or the otheroi" the parts due to the severe stresses set up.

l' have discovered that by associating with 'the parts oi unequalcoelhcient o'l expansion, a body of material whose coeiiicient otexpansion is higher than that ot either of the said parts in such mannerthat in expanding it tenus to tighten and in contraction to loosen theconnection therebetween, am able to maintain a tight connect-ion betweenthe parts regardless of the temperature changes, this being;` due to thefact that the material of relative-ly high coefficient o expansion bothXpands and contracts more rapidly than either or" the other parts.7'riegardless then of the unevenness of the expansion, this: body willmaintain continuously a tight connection, and upon coolingof the` partsand consequent contraction. the more rapid contraction ot the materialpermits free expansion ot the other Serial No. 506,985.

Fig. 2, is a longitudinal section of' a wedge Y constituting anembodiment of my invention, and

F 1g. 3, is a. view 1n perspective or" the wedge.

lilith reference to the drawings, l indi-v cates a portion of the anvilof a drop hammer or similar machine, and 2 an anvil cap which is mountedin a recess 3 in the anvil, the sides 4l ot the recess being beveledinwardly and the lower portion 5 of the cap being dovetailed, as clearlyshown. The dovetailed portion 5 of the cap is somewhat narrower than therecess 3 in the anvil, and in the present instance a wedge 6 is insertedin the space between the cap and the anvil to maintain a tight litbetween these elements.

In the present instance l have illustrated the material of relativelyhigh coeliicient of expansion applied in the form of inserts in thesides ot' the wedge 6, these inserts, indicated by the referencenumerals 7, 7, being,r snitably secured in recesses in the sides of thewedge 6, as clearly shown in the drawings. ln Ainfactice, the wedge 6 isapplied in a manner exactly similar to the wedge oi' the usual. torni,being driven in to lorin :i tight lit between the anvil and the cap. isthe parts become heated during` operation ol the macl'iine, the insertsT, which in the present may be ot copper, will 'tend to expand, and dueto their relatively great expansion will taire up any loosenessdeveloping between the anvil and the cap due to uneven expansion otthese parts. Vlhere will be found no necessity for adjusting the wedgeto a new position to taire up this developing looseness. ris the partecool alter operation oit t-he machine ceases, all. danger from unevencontraction is eliminated due to the fact that the inserts contract morequickly than either the anvil or the cap and thereby git/*e space l'orthe contraction of the anvil.

it will be apparent `that the invention in principle will findapplications other than that herein set forth, and further that numerousmodifications in the method oft application are possible with nodeparture from the essential features of the invention.

l. rl`he combination with a pair of associated bodies having differentcoeiiicients oi? expansion, of an element constituting securing meansbetween said members and having a coefficient oit expansion higher thanthat oi' either oi' said associated members.

E2. Thev combination with a pair of associated members of differentcoeicients oi expansion, one of said members having a recess occupiedbythe other, of an element inserted betwveenthe members .for securingthe one in the other and comprising a material having a coeiiicient oi'expansion higher than that of eitheroi the members.

3. The combination With a pair ci associated members of differentcoelicents ot expansion, one et said members having a recess occupied bythe other, oi an element inserted between the members ter securing theone in the other and comprising a body having' inserted in the tacethereofv a mate-v rial of higher coeiiicient of expansion than that oiteither of said members.

Il. The combination with an anvil, oi an va recess, vof an anvil capadapted to iit Within the recess, and means for securing the cap in therecess comprising a member `inserted between the anvil and the can andcomprising ya material having a coeiiicient;

of expansion higher than that of either the said anvil or cap. t

(5. rihe method of compensating for un'- equal expansion and contractionin two bodies, one of which is confined Within a recess in the other,which consists ininserting between the bodies an element having acoeiiicient of expansion higher than either.

7. The combination with a pair of menibers subject to different degreesot explansion and contraction, one of which members is confined Within arecess in theA other, et a 4securing element inserted between Athemembers and having a coefficient oif expansion exceeding that of either.

lVM. HERBERT DERBYSHRE, Jia.

